Effects of aging on phase constitution, lattice parameter and mechanical properties of Ti-4mol%Au near-eutectoid alloy

Abstract

Effects of aging on phase constitution, lattice parameters and mechanical properties of Ti-4mol%Au near-eutectoid alloy were investigated. The alloy was fabricated by Ar arc-melting method, followed by homogenization at 1273 K for 3.6 ks. The ingot was cold-rolled with 95% reduction in thickness, solution treated at 1173 K for 0.9 ks and quenched into ice water. It was found that the apparent phase after the solution treatment was a supersaturated solid solution of α (hcp) phase. This supersaturated α-phase is termed αm, hereafter. The apparent phase of the aged alloys was αm regardless of the aging temperature from 373 to 1073 K for 3.6 ks. The 0.2% flow stress was decreased as the aging temperature increased. On the other hand, by the isothermal aging at 973 K, Ti3Au with A15 structure was formed and the volume fraction of Ti3Au increased with increasing aging time. The 0.2% flow stress of the materials was decreased as the volume fraction of Ti3Au increased. This indicates that the Ti3Au precipitations are not effective on strengthening of the Ti-Au alloy. © 2007 The Japan Institute of Metals.